1. Field of the Invention
This invention relates to the laminating art in which objects are heat-sealed with leaves of plastic film which form a pouch or covering over the object such as an identification card.
2. Description of the Prior Art
The use of polyester film carriers, and particularly polyethylene terephthalate (Mylar) in combination with heat-reactivatible coatings, such as, polyethylene, ethylene-ethyl acrylate, or similar adhesives, has become quite popular as a useful laminating material. Such films are utilized as described in U.S. Pat. Nos. 3,684,638 and 3,711,355 for covering wallet-sized identification cards. Such a covering prevents tampering with photographs and date indicia on the identification card.
When employed in conjunction with identification cards produced as Polaroid (a registered trademark of Polaroid Corporation) photos, it is important that a high integrity bond be formed between the covering film and the photo even though the surface may remain wet after the development process. Consequently, special coatings have been developed to permit bonding between the heat reactivatible adhesive surface and the photo. Recently, the Polaroid Corporation has developed an improved color film under the trademark Polacolor No. 2 which obsoletes all Polacolor No. 1 film in the marketplace. It has been noted that pouch film previously treated to stick to wet Polacolor No. 1 films will not stick to wet Polacolor No. 2 film. Polaroid Corporation has developed a treatment known as Polaroid No. 1406 adhesive solution also known as Polaroid adhesive No. 2 which, when applied to the heat reactivatible surfaces of a pouch film material, permits bonding of the film to an all-photo identification card. Such an I.D. card pouch is shown at 10 in FIG. 1. An I.D. card 11 having a continuous photo surface with both a photo image 12 and indicia 13 is positioned between a front film leaf 15 and a back film leaf 16. Heat reactivatible coatings 17 and 19 shown in FIG. 2 are respectively coated on the inside surfaces of polyethylene terephthalate base films 18 and 20 forming the front and back leaves.
The leaves 15 and 16 may or may not be joined along the edge 21, as shown in FIG. 1.
In order to permit the all photo identification card 11 to adhere to the covering leaves 15 and 16, a layer of Polaroid 1406 adhesive solution is placed as a coating 22 on the inside surface of the heat reactivatible coating 17 and as a coating 23 on the inside surface of the heat reactivatible coating 19. This adhesive solution permits the leaves to firmly bond to surfaces of the all-photo I.D. card.
In many applications it is more advantageous, however, to utilize an identification card of Paper Stock on which a Polaroid photograph is positioned. If the above laminating techniques are utilized with such a hybrid identification card, problems occur since the heat reactivatible adhesive treated with the Polaroid No. 1406 does not bond well to paper card stock surfaces and bonds poorly to photos having film surfaces other than Polacolor No. 2 such as Polaroid Polacolor No. 1 film. Also with the prior art laminating techniques, the edge if the card is susceptible to deterioration as the result of atmospheric moisture and bond integrity consequently decreases with continued exposure to such conditions. Finally, the exact position of the photograph on the paper card stock may differ for various applications.